The detergent industry has for more than 30 years implemented different enzymes in detergent formulations, most commonly used enzymes includes proteases, amylases and lipases each adapted for removing various types of stains. In addition to the enzymes detergent compositions typically include a complex combination of ingredients. For example, most cleaning products include surfactant system, bleaching agents or builders.
The proteases are one of the standard ingredients of all kinds of detergents ranging from those used for household laundering to reagents used for cleaning contact lenses or dentures. In textile laundry the proteases remove protein stains such as grass, blood, egg and human sweat. These organic stains have a tendency to adhere strongly to textile fibres. Proteases hydrolyse the proteins in the stains and break them down into more soluble polypeptides or free amino acids.
Alkaline serine proteases are the most important group of protease exploited commercially in the detergent industry. Subtilisins are a prototypical group of bacterial serine proteases used extensively in detergents due to their stability and activity at high temperature and alkaline pH. A commercially important subtilisin used extensively in the detergent industry is Savinase®.
New interest in properties such as low-temperature performance and development of new detergent compositions has led to renewed interest for new proteases and other types of detergent enzymes. The search for new proteases is not limited to subtilisins, but is also directed at finding new protease backbones suitable for application in detergent products.
Metalloproteases are a group of proteases which have not yet been commercially applied in detergent industry, mainly due to low stability in detergent compositions as well as under the conditions during the wash process. Metalloproteases are proteolytic enzymes having an absolute requirement for metal ion for their activity. Most metalloproteases are zinc-dependent, although some use other transition metals. Metalloproteases have been widely used in different industries like food and brewing industry. One group of metalloproteases is the M4 family metalloproteases which have been used in various applications. For example, the M4 metalloprotease from Bacillus amyloliquefaciens, also known as Neutrase®, has been used for many years as an additive in various food and feed products. This metalloprotease has also been described for use in detergent and cleaning compositions and processes e.g., in WO 2007/044993, use of storage-stable metalloproteases in detergent or WO 2009/058518, and EP 1 288 282, which describes a blend of a metalloprotease and a serine protease for use in dish washing. WO 2000/60042 also describes detergent compositions containing a metalloprotease. And WO 2007/044993 describes the use of the metalloproteases Neutrase® and/or “NprE” for use in detergent applications.
However, known metalloproteases are very unstable under conventional wash conditions and in conventional detergent compositions. Thus, the use of metalloproteases in detergents and in wash and cleaning processes has not yet been commercialized.
Therefore, there remains a need for metalloproteases having increased stability under wash conditions and/or in detergent compositions. The present invention is directed to providing such enzymes.
A nucleotide sequence encoding a putative metalloendopeptidase has been identified in Chryseobacterium gleum. The encoded protein UNIPROT:D7VZJ2 is 91.6% identical to the metalloprotease of the present invention.